[Show abstract][Hide abstract] ABSTRACT: In this paper, several experiments were conducted to further clarify the
formation mechanism of self organized void array induced by a single laser
beam, including energy-related experiments, refractive-index-contrast-related
experiments, depth-related experiments and effective-numerical-aperture
experiment. These experiments indicate that the interface spherical aberration
is indeed responsible for the formation of void arrays.
Chinese Physics B 01/2014; 23(7). · 1.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report on the preparation of Ga/Al nanoalloys embedded glass‐ceramic by heat treatment as well as femtosecond laser irradiation. The Ga/Al nanoalloys embedded glass‐ceramic exhibits intense extinction in the visible region, as well as superior optical nonlinearities. The third‐order nonlinear optical properties of the glass‐ceramics were investigated by employing Z‐scan technique. The maximum nonlinear extinction coefficient β and nonlinear refraction γ value reached 1.14 × 10−11 m/W and 2.01 × 10−17 m2/W, respectively. Three‐dimensional Ga/Al nanoalloys embedded structures were also achieved in glass by scanning the focused femtosecond laser beam. These results may find applications for the fabrication of ultrafast optical switches and diffractive optical elements.
Journal of the American Ceramic Society 01/2012; 95(2). · 2.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report on a simple and universal method for fabricating various kinds of metal and semiconductor (Si, Ge, Bi, and Cu) nanoparticle–glass composites by using metallic Al as a reducing agent in the raw materials of the glass batches. By taking advantage of the redox equilibrium that sets up between the Al reducing agent and various oxides, crystal nuclei such as Si and Ge atom clusters are already formed during the melt-quenching stage. During the subsequent heat-treatment stage, the nanoparticles grow on the nuclei by a process of diffusion. The nanoparticle size can be controlled by heat-treatment temperature and holding time. The fabricated nanoparticle–glass composites exhibit large third-order optical nonlinearities (χ3 up to 10–8 esu) and an ultrafast response time (within picoseconds), which makes them possible to manufacture ultrafast all-optical switches.
The Journal of Physical Chemistry C. 11/2011; 115(50):24598–24604.
[Show abstract][Hide abstract] ABSTRACT: Permanent microscale bubbles with varied size and number density are induced in borosilicate glasses by adjusting the focusing depth (FD) of a tightly focused femtosecond laser. With continuously increasing of the focusing depth, the average size of generated bubbles experiences an increase–decrease process. However, the number density of generated bubbles experiences an opposite changing process compared to the change of the size. The possible mechanism for the bubble generation and changing with the focusing depth has been discussed.
[Show abstract][Hide abstract] ABSTRACT: We report on different refractive index change (RIC) behavior in borosilicate glasses induced by focused 1 kHz and 250 kHz femtosecond (fs) laser irradiation. The influence of fs laser irradiation condition and annealing temperature on RIC was examined. Absorption, electron spin resonance and Raman spectra, and transmission electron microscope were used to clarify the mechanisms of the RIC. Smaller RIC (up to 10−4) was observed after 1 kHz fs laser irradiation, while larger RIC (up to 10−1) was detected after 250 kHz fs laser irradiation, which were ascribed to the formation of color centers and precipitation of nanocrystals, respectively. The result highlights that the mechanisms of RIC induced by fs laser can be very different depending on the irradiation conditions.
[Show abstract][Hide abstract] ABSTRACT: We report the formation of inverted microstructures inside glasses after femtosecond laser irradiation by tuning the refractive index contrast between the immersion liquid and the glass sample. By using water as well as 1-bromonaphthalene as immersion liquids, microstructures with similar shape but opposite directions are induced after femtosecond laser irradiation. Interestingly, the elemental distribution in the induced structures is also inverted. The simulation of laser intensity distribution along the laser propagation direction indicates that the interfacial spherical aberration effect is responsible for the inversion of microstructures and elemental distribution.
[Show abstract][Hide abstract] ABSTRACT: With the irradiation by femtosecond (fs) laser with high repetition rate, GeS2 micro/nano-crystalline formation and microstructural modification occurred in pseudo-binary GeS2–In2S3 glass, while almost no similar change was observed in GeS2 glass. The addition of In2S3 is beneficial for the precipitation of GeS2 micro/nano-crystals. It is expected that functional micro/nano-crystals can be controllably prepared in chalcogenide glasses by fs laser irradiation through glass composition design.
Journal of Non-Crystalline Solids 01/2011; 357:2392-2395. · 1.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report the elemental redistribution in a Bi-doped oxyfluoride glass induced by a 250-kHz femtosecond laser. Our results show that the relative concentration of the network modifier Bi ions in the modified region is higher than that in the unmodified regions. However, the relative concentration of the network modifier Ca ions is opposed to that of Bi ions. This is the first time to observe the differential distribution of relative concentration between the network modifiers. These results are important to practical application in the fabrication of waveguide lasers and amplifiers in active ion-doped glasses.
Journal of Non-Crystalline Solids 01/2011; 357:2384-2386. · 1.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Transparent glass samples doped with bismuth nanoparticles are prepared by heat treatment of as-made glass samples. According to the results of X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectra, Bi nanoparticles are well distributed inside glasses after heat treatment. The average size of Bi nanoparticles increases with the increasing of heat treatment temperature. Because of the size effect and multiple scattering of nanoparticles, the fundamental absorption edge shows a red-shift behavior with the increasing of heat treatment temperature. Nonlinear optical properties of Bi nanoparticles doped glasses are investigated by using Z-scan technique. The maximum value of χ(3) of the glasses is estimated to be 2.49 × 10− 7 esu at 800 nm. These results indicate that Bi nanoparticles doped glasses may be promising as material for optical switching.Research Highlights► Transparent glass samples doped with bismuth nanoparticles are prepared by melt-quenching and subsequent annealing. ► X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectra analyses confirmed the formation of Bi nanoparticles inside glass. ► Because of the size effect and multiple scatting of nanoparticles, the fundamental absorption edge shows a red-shift behavior with increasing heat treatment temperature. ► Nonlinear optical properties of Bi nanoparticles doped glasses are investigated by using Z-scan technique.
Journal of Non-Crystalline Solids 01/2011; 357:2312-2315. · 1.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper, an interesting inverted structure, fabricated by focusing femtosecond laser pulses through two different objective lenses (an oil-immersion objective lens and a dry objective lens), is reviewed. According to the interface spherical aberration theory, reasonable models are built and the simulated laser fluence in the focal region is given. The distribution of laser fluence agrees with the structural characteristics of the experimentally obtained void array. We propose that the monotonic tendency that the aberration function changes with the azimuth angle determines the final ‘growth’ direction of the void array.
Journal of Physics D Applied Physics 01/2011; 44(49). · 2.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Crystalline Ge was induced space selectively inside a borosilicate glass by 800 nm, 250 kHz femtosecond laser irradiation. Micro-Raman spectra and x-ray diffraction analysis confirmed that the laser-induced crystals were cubic Ge. A periodic structure consisting of Ge crystalline lines was inscribed in the glass sample by continuously moving the focal point of the laser beam. Large third-order nonlinear optical properties and ultrafast response time were observed from the crystallization region owing to highly optical nonlinearity of Ge crystals. These results may find some applications in fabrication of functional optical and photonic devices, such as optical circuits.
[Show abstract][Hide abstract] ABSTRACT: Transparent glasses containing copper nanoparticles are promising materials for ultrafast all-optical switches in the THz region due to their wide range of resonant absorption frequencies, ultrafast time response, as well as large third-order nonlinear optical coefficients associated with the surface plasmon resonance (SPR) in the visible region. In this paper, three dimension controllable precipitation of copper nanoparticles inside a borosilicate glass by irradiation of femtosecond laser pulses is studied. According to the designed program, different patterns made up of copper nanoparticles can be induced inside the glass sample. Absorption spectra are used to confirm the precipitation of copper nanoparticles. The precipitated nanoparticles can be space-selectively “dissolved” by the second time femtosecond laser irradiation. The involved mechanisms are discussed.Research Highlights► Cu nanoparticles are induced by femtosecond laser directly writing. ► The Cu nanoparticles are concentrated at the bottom of the modified zone. ► The Cu nanoparticles can be dissolved with a second time laser irradiation.
Journal of Non-Crystalline Solids 01/2011; 357:2380-2383. · 1.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Three individual primary colors were generated from only one piece of Er3+–Eu3+ co-doped oxygen-deficient germanate glass under UV light irradiation. Blue, green, and red emissions were originated from Ge-related oxygen-deficient defect centers (GODCs), Er3+ ions, and Eu3+ ions, respectively. Detailed photoluminescence spectra, decay curve analyses, and electron paramagnetic resonance measurements were carried and the results indicate the existence of energy transfer between Er3+ and Eu3+ ions, GODCs and Eu3+ ions.
Journal of Alloys and Compounds 01/2011; 509(22):6462-6466. · 2.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We show that uniform nanoripples can be produced on the sidewalls of the micro-cell vertically embedded in fused silica glass by femtosecond laser direct ablation. The nanoripples can be used for homogeneous liquid crystal (LC) alignment with different azimuthal angles. The azimuthal anchoring energy at the interface between the LC and nanoripples is obtained by measuring the twist angle of LC director in the fabricated twisted nematic LC micro-cell. This method allows for fabrication of LC micro-cells integrated in glass chip with three-dimensional (3D) configurations, opening a new venue to fabrication of 3D miniaturized LC devices.
Chemical Physics Letters 09/2010; 498(1-3):188-191. · 2.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Controllable microstructures are formed on a glass surface after irradiation of a focused 800 nm, 250 KHz femtosecond laser beam. Field-emission scanning electron microscope and 3D measuring laser microscope images reveal that the induced structures are circular and linear protuberances and can be controlled from 10 microm to hundreds of micrometers in width, and from 1 microm to tens of micrometers in height. The protuberance structure is proposed to be formed as a consequence of the laser-induced high temperature and pressure owing to linear and nonlinear absorption near the laser focal point, and low softening and melting temperature of the glass sample.
[Show abstract][Hide abstract] ABSTRACT: The redistribution of elements in a multicomponent oxyfluoride glass is induced by a 250 kHz femtosecond laser. Elemental distribution in the cross section of the modified region along the laser propagation axis is analyzed by an electron microprobe analyzer. The results indicate that the relative concentrations of network formers of the glass are higher in the central area of the modified region and lower in the periphery of the modified region compared with the unirradiated areas. However, the relative concentrations of network modifiers are as opposed to that of network formers. Fluorescence spectra confirm that the distribution of fluorescence intensity of Yb(3+) in the modified region is consistent with that of its concentration. The effects of spherical aberration of the incident beam on the elemental redistribution are also discussed.
[Show abstract][Hide abstract] ABSTRACT: α-Bi2O3 nanoparticles have been produced by femtosecond laser ablation in ethanol at room temperature. Their crystal structure, crystal phase, shape and size distribution, and photophysical property are investigated using X-ray diffraction, Raman, transmission electron microscopy (TEM), high-resolution TEM and UV–vis spectroscopy. The α-Bi2O3 nanoparticles produced by laser ablation with two particle size population distributions having the mean particle size of ∼10 and ∼60 nm exhibited a good photocatalytic activity on the photodegradation of indigo carmine under 365 nm light emitting diode irradiation.
Journal of Alloys and Compounds 01/2010; · 2.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report on highly localized precipitation of copper nanoparticles in borate glasses by irradiation with femtosecond laser pulses. The area in the vicinity of the laser focal point of an 800nm femtosecond laser inside the glass sample became red due to the precipitation of copper nanoparticles after the femtosecond laser irradiation. The precipitation of copper nanoparticles was confirmed by transmission electron microscopy images, electron energy-loss spectra and absorption spectra. The average power of the femtosecond laser and the irradiation time are two important factors related to the formation of the precipitates. The mechanism of the precipitation of copper nanoparticles is discussed.
Chemical Physics Letters 01/2010; 485(1):91-94. · 2.15 Impact Factor